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| Theoretical temporal dynamic of objective and subjective cognitive decline throughout AD continuum. The figure shows the hypothetical differences, during the transition from preclinical AD to dementia, between Subjective Cognitive Decline (SCD) and Objective Cognitive Decline (OCP). At final stages of preclinical AD, SCD is a better early marker than OCP for the transition to Mild Cognitive Impairment (MCI).As disease progresses, cognitive performance decreases and at prodromal stage, (MCI) both SCD and OCP are below cutoff. Indeed, as disease progresses SCD usually disappears leading to a deficit of self-awareness about the own disabilities namely anosognosia.
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Introduction:
Researchers are searching for clinical instruments to predict amyloid positivity for disease classification. Informant-based reports could detect disease status. This study compares subjective memory complaints captured by informant-based reports between positron emission tomography (PET)-positive and PET-negative patients and hypoth...
Citations
... These stages have become focal points of recent research. Typically, the progression starts with normal cognition, transition into subjective cognitive decline (SCD)-a decrease in cognitive ability that is subjectively perceived compared to prior normal status but irrelevant to objective cognitive test results [12]-and eventually evolves into mild cognitive impairment (MCI), a condition characterized by a noticeable decline in cognitive abilities that does not interfere with daily functioning but increases the risk of Alzheimer disease or other types of dementia [13][14][15]. This transitional state of MCI poses a relatively high risk of progression to dementia, with some studies highlighting an estimated annual progression rate of approximately 10% [15][16][17][18]. ...
Background
Understanding mild behavioral impairment, a relatively recent notion in neuropsychological studies, provides significant insights into early behavioral indicators of cognitive decline and predicts the onset of dementia in older adults. Although the importance of understanding mild behavioral impairment is acknowledged, comprehensive reviews of its correlates with older adults are limited.
Objective
This scoping review aims to identify the impact of mild behavioral impairment on health outcomes in older adults and the factors associated with mild behavioral impairment.
Methods
The review will adhere to the Joanna Briggs Institute’s methodological principles for scoping reviews. We will include studies focusing mainly on mild behavioral impairment in older adults, with the literature on this topic being limited to the period from 2003 to the present. Other clinical diagnoses, such as cognitive impairment, Parkinson disease, and multiple sclerosis, will not be included. We will use databases including PubMed (MEDLINE), CINAHL, Web of Science, Embase, PsycINFO, Cochrane, and Scopus for relevant articles published in English. Both gray literature and peer-reviewed articles will be considered during screening. Three independent reviewers will extract data using a predefined data extraction tool. Extracted data will be presented using tables, figures, and a narrative summary aligned with review questions, accompanied by an analysis of study characteristics and categorization of mild behavioral impairment correlates.
Results
The results will be presented as a descriptive summary, structured according to the associated factors related to mild behavioral impairment, and the health outcomes. Additionally, the data on study characteristics will be presented in tabular format. An exploratory search was conducted in July 2023 to establish a comprehensive search strategy, and iterative refinements to the scoping review protocol and formalization of methods were completed. A follow-up search is planned for May 2024, with the aim of submitting the findings for publication in peer-reviewed journals.
Conclusions
To our knowledge, this would be the first study to map the literature on the health-related factors and outcomes of mild behavioral impairment. The findings will support the development of interventions to prevent the occurrence of mild behavioral impairment and mitigate the negative outcomes of mild behavioral impairment.
International Registered Report Identifier (IRRID)
DERR1-10.2196/60009
... consensus that extends AD to the phase before MCI, during which cognitive tests may not detect any deficits. [8][9][10][11] Relying solely on SCD is inadequate for the reliable detection of preclinical AD, highlighting the need for exploring various cognitive domains beyond memory. 4,5,12 Previous research suggests that depressive symptoms play a crucial role in influencing how individuals perceive and report cognitive decline. ...
Objective:
Subjective cognitive decline (SCD) refers to self-reported memory loss despite normal cognitive function and is considered a preclinical stage of Alzheimer's disease. This study aimed to examine the mediating effects of depression and Instrumental Activities of Daily Living (IADL) on the association between the scoring of Clinical Dementia Rating Scale-Sum of Boxes (CDR-SB) and Subjective Cognitive Decline Questionnaire (SCD-Q).
Methods:
A sample of 139 community-dwelling older adults aged 65-79 with normal cognitive function completed the SCD-Q, a comprehensive neuropsychological battery, and functional/psychiatric scales. We conducted 1) a correlation analysis between SCD-Q scores and other variables and 2) a path analysis to examine the mediating effects of depression and IADL on the relationship between CDR-SB and SCD-Q.
Results:
CDR-SB was found to be indirectly associated with SCD-Q, with depressive symptoms mediating this relationship. However, no direct association was observed between SCD-Q and CDR-SB. Additionally, IADL was not associated with SCD-Q and did not mediate the relationship between CDR-SB and SCD-Q. The model fit was acceptable (minimum discrepancy function by degrees of freedom divided [CMIN/DF]=1.585, root mean square error of approximation [RMSEA]=0.065, comparative fit index [CFI]=0.955, Tucker-Lewis index [TLI]=0.939).
Conclusion:
Our results suggest that SCD-Q is influenced by depressive symptoms, but not by IADL. The role of depressive symptoms as a mediator between CDR-SB and SCD-Q indicates that psychological factors may contribute to the perception of SCD. Therefore, interventions targeting depression may mitigate the concerns associated with SCD and reduce feelings of worse performance compared to others of the same age group.
... These stages have become focal points of recent research. Typically, the progression starts with normal cognition, transition into subjective cognitive decline (SCD)-a decrease in cognitive ability that is subjectively perceived compared to prior normal status but irrelevant to objective cognitive test results [12]-and eventually evolves into mild cognitive impairment (MCI), a condition characterized by a noticeable decline in cognitive abilities that does not interfere with daily functioning but increases the risk of Alzheimer disease or other types of dementia [13][14][15]. This transitional state of MCI poses a relatively high risk of progression to dementia, with some studies highlighting an estimated annual progression rate of approximately 10% [15][16][17][18]. ...
BACKGROUND
Understanding mild behavioral impairment, a relatively recent notion in neuropsychological studies, provides significant insights into early behavioral indicators of cognitive decline and predicts the onset of dementia in older adults. Although the importance of understanding mild behavioral impairment is acknowledged, comprehensive reviews of its correlates with older adults are limited.
OBJECTIVE
This scoping review aims to identify the impact of mild behavioral impairment on health outcomes in older adults and the factors associated with mild behavioral impairment.
METHODS
The review will adhere to the Joanna Briggs Institute’s methodological principles for scoping reviews. We will include studies focusing mainly on mild behavioral impairment in older adults, with the literature on this topic being limited to the period from 2003 to the present. Other clinical diagnoses, such as cognitive impairment, Parkinson disease, and multiple sclerosis, will not be included. We will use databases including PubMed (MEDLINE), CINAHL, Web of Science, Embase, PsycINFO, Cochrane, and Scopus for relevant articles published in English. Both gray literature and peer-reviewed articles will be considered during screening. Three independent reviewers will extract data using a predefined data extraction tool. Extracted data will be presented using tables, figures, and a narrative summary aligned with review questions, accompanied by an analysis of study characteristics and categorization of mild behavioral impairment correlates.
RESULTS
The results will be presented as a descriptive summary, structured according to the associated factors related to mild behavioral impairment, and the health outcomes. Additionally, the data on study characteristics will be presented in tabular format. An exploratory search was conducted in July 2023 to establish a comprehensive search strategy, and iterative refinements to the scoping review protocol and formalization of methods were completed. A follow-up search is planned for May 2024, with the aim of submitting the findings for publication in peer-reviewed journals.
CONCLUSIONS
To our knowledge, this would be the first study to map the literature on the health-related factors and outcomes of mild behavioral impairment. The findings will support the development of interventions to prevent the occurrence of mild behavioral impairment and mitigate the negative outcomes of mild behavioral impairment.
INTERNATIONAL REGISTERED REPORT
DERR1-10.2196/60009
... In other studies, self-reported memory problems and APOE e4 status have been shown to be associated with faster preclinical cognitive decline 13,14 or increased risk of progression to dementia. 15,16 Thus, a wide and diverse range of risk factors for early cognitive decline have been identified, subsets of which have been examined across a diversity of studies. ...
Cognitive decline in Alzheimer’s disease and other dementias typically begins long before clinical impairment. Identifying people experiencing subclinical decline may facilitate earlier intervention. This study developed cognitive trajectory clusters using longitudinally-based random slope and change point parameter estimates from a Preclinical Alzheimer’s disease Cognitive Composite and examined how baseline and most recently available clinical/health-related characteristics, cognitive statuses and biomarkers for Alzheimer’s disease and vascular disease varied across these cognitive clusters.
Data were drawn from the Wisconsin Registry for Alzheimer’s Prevention, a longitudinal cohort study of adults from late midlife, enriched for a parental history of Alzheimer’s disease and without dementia at baseline. Participants who were cognitively unimpaired at the baseline visit with >= 3 cognitive visits were included in trajectory modeling (n=1068). The following biomarker data were available for subsets: positron emission tomography (PET) amyloid (Amyloid: n = 367; [C-11]PiB: Global PiB distribution volume ratio); PET tau (Tau: n = 321; [F-18]MK-6240: primary regions of interest Meta-Temporal composite); MRI neurodegeneration (Neurodegeneration: n = 581; hippocampal volume and global brain atrophy); T2-FLAIR MRI white matter ischemic lesion volumes (Vascular: White matter hyperintensities; n=419); and plasma pTau217 (n=165). Posterior median estimate person-level change points, slopes pre- and post- change point, and estimated outcome (intercepts) at change point for cognitive composite were extracted from Bayesian Bent-Line Regression modeling and used to characterize cognitive trajectory groups (K-means clustering). A common method was used to identify Amyloid/Tau/Neurodegeneration/Vascular biomarker thresholds. We compared demographics, last visit cognitive status, health-related factors and Amyloid/Tau/Neurodegeneration/Vascular biomarkers across the cognitive groups using ANOVA, Kruskal-Wallis, Chi-square, and Fisher’s exact tests.
Mean(SD) baseline and last cognitive assessment ages were 58.4(6.4) and 66.6(6.6) years, respectively. Cluster analysis identified 3 cognitive trajectory groups representing Steep: n = 77(7.2%); Intermediate: n = 446(41.8%); and Minimal: n = 545(51.0%) cognitive decline. The Steep decline group was older, had more females, APOE e4 carriers, and Mild cognitive impairment/dementia at last visit; it also showed worse self-reported general health-related and vascular risk factors and higher Amyloid, Tau, Neurodegeneration and White matter hyperintensities positive proportions at last visit.
Subtle cognitive decline was consistently evident in the steep decline group and was associated with generally worse health. In addition, cognitive trajectory groups differed on etiology-informative biomarkers and risk factors, suggesting an intimate link between preclinical cognitive patterns and Amyloid/Tau/Neurodegeneration/Vascular biomarkers differences in late middle-aged adults. The result explains some of the heterogeneity in cognitive performance within cognitively unimpaired late middle-aged adults.
... And the associations of risk factors such as sex and education with amyloid pathology are still unclear among individuals with SCD [22,23]. Notably, the results were not always consistent due to the differences in study settings, SCD assessment methods, and characteristics of populations [24,25]. Also, there is still no research on SCD-plus characteristics associated with amyloid pathology in China. ...
Background
Subjective cognitive decline (SCD) is considered as a preclinical hallmark of Alzheimer’s disease (AD). However, the characteristics of SCD associated with amyloid pathology remain unclear.
Objective
We aimed to explore the associations between SCD characteristics with amyloid pathology.
Methods
Using logistic regression analyses, we analyzed the associations between cerebrospinal fluid (CSF) amyloid pathology with AD risk factors, SCD-specific characteristics (onset of SCD within the last five years, age at onset ≥60 years, feelings of worse performance, informant confirmation of complaints, worries, other domains of cognition complaints), as well as subthreshold depressive and anxiety symptoms among individuals with SCD.
Results
A total of 535 SCD individuals with available CSF Aβ42 information from the Chinese Alzheimer’s Biomarker and LifestylE (CABLE) study (mean age of 63.5 years, range 40 to 88 years; 47.10% female) were enrolled. The characteristics of informant confirmation of complaints (OR, 95% CI = 2.00, 1.19–3.36), subthreshold depressive symptoms (OR, 95% CI = 2.31, 1.05–5.09), and subthreshold anxiety symptoms (OR, 95% CI = 2.22, 1.09–4.51) were found to be significantly associated with pathological amyloid in multivariate analyses when adjusting for age, sex, education, and APOE ɛ4. Besides, age and females were observed risks for amyloid pathology in subscale analyses. Nonetheless, we did not find any associations of other SCD-specific characteristics with amyloid pathology in this study.
Conclusion
Our study suggested that informant confirmed complaints and subthreshold psychiatric symptoms might be critical for discriminating AD-related SCD from non-AD related SCD.
... Research has suggested that subjective cognitive decline (SCD), or the self-reported experience of subtle changes in cognitive functioning without any measurable changes in neuropsychological test performance [25], may be a preclinical marker of AD [3]. For example, individuals who endorse SCD have an increased risk of developing AD compared to the general population [3,49,53]. ...
... Research has suggested that subjective cognitive decline (SCD), or the self-reported experience of subtle changes in cognitive functioning without any measurable changes in neuropsychological test performance [25], may be a preclinical marker of AD [3]. For example, individuals who endorse SCD have an increased risk of developing AD compared to the general population [3,49,53]. Typically reported as increased confusion or memory loss, the prevalence of SCD among adults aged 60 and older is around 25% [50]. Therefore, SCD may prove to be an effective target for early intervention. ...
... Participant inclusion criteria for this specific study were as follows: (1) cognitively normal/healthy (NC/ SCD −) status at their baseline visit (e.g., no mild cognitive impairment, MCI), (2) no report of stroke, (3) had completed at least two cognitive assessments, (4) completed the questionnaire assessing memory complaints, and (5) at least 55 years of age at baseline. A clinical diagnosis of cognitive status was completed using a three-stage process including computer scoring of cognitive tests, clinical judgment by a neuropsychologist, and diagnostic classification by a clinician based on criteria of the joint working group of the National Institute on Aging and the Alzheimer's Association (NIA-AA) [39]. ...
Background
The identification of biomarkers for early detection of Alzheimer’s disease (AD) is critical to the development of therapies and interventions targeted at symptom management and tracking the pathophysiology of disease. The endorsement of subjective cognitive decline (SCD) has emerged as a potential indicator of early change in cognitive status that may be predictive of future impairment at a time when measurable declines in neuropsychological performance cannot be detected. While there are numerous findings revealing sex differences in the prevalence of AD, there is a paucity of research examining sex differences in SCD. Therefore, the goal of this project was to determine if the relationship between the endorsement of SCD and future cognitive changes differ as a function of biological sex.
Methods
A sample of 3019 male and female healthy older adults (2188 without SCD, 831 with SCD), with a mean follow-up time of 5.7 years, were included from the Rush Alzheimer’s Disease Center Research Sharing Hub. Linear regressions were performed to determine group differences in baseline cognitive scores, while linear mixed-effects models were completed to determine group differences in the rate of cognitive change over time.
Results
Individuals endorsing SCD had significantly lower baseline cognitive scores and increased rates of decline in all cognitive domains compared to those without SCD. Males exhibited significantly lower scores in baseline performance in global cognition, episodic memory, and perceptual speed regardless of SCD classification. Females with SCD were found to decline at significantly faster rates than both males with SCD and males and females without SCD in all cognitive domains over a maximum 15-year follow-up period.
Conclusions
SCD is related to lower baseline cognitive performance and faster cognitive decline compared to those who do not endorse SCD. Females with SCD have the fastest rate of decline suggesting that SCD may be more predictive of future decline in females than in males. Targeted assessments of SCD may allow for the identification of individuals for inclusion in intervention trials, and other research studies, aiming to attenuate casual disease processes, which may ultimately aid in the mitigation of sex disparities in AD.
... In addition, control participants in our study were people with SCD resulted unimpaired after neuropsychological testing. In this regard, some authors suggested that SCD may present in a preclinical phase of dementia, prior to the MCI and any observable cognitive deficits (Ávila-Villanueva & Fernández-Blázquez, 2017;Cheng et al., 2017). Indeed, older adults with no objective cognitive deficits and subjective memory complaints were twice as likely to develop dementia compared with individuals without complaints (Mitchell et al., 2014). ...
Objective: The present study aimed at investigating the sensitivity and specificity of the NeuroPsychological Examination (NPE), a systematic collection of cognitive signs and symptoms based on the observation of the patient’s behavior during a clinical interview, in detecting Mild Cognitive Impairment (MCI). Method: 475 participants, 208 suffering from MCI, 188 suffering from dementia and 79 subjective cognitive decline (SCD), have been assessed using NPE for the presence of signs and symptoms of cognitive impairment. Receiver operating characteristic (ROC) curve analysis and the Youden’s test were used to determine the more appropriate cutoff points for the number of neuropsychological signs at the NPE that enabled to discriminate SCD from MCI, SCD from dementia and MCI from dementia. A sensitivity and specificity analysis and comparisons among the three groups were conducted. Results: The mean number of signs at the NPE were 1.73 for SCD, 7.98 for MCI and 12.82 for dementia. Pairwise comparisons among the three group of participants showed significant differences (SCD vs. MCI, p < .001, r = −0.66; SCD vs. dementia, p < .001, r = −0.76; MCI vs. dementia, p < .001, r = −0.44). The criterion of 3 signs at the NPE showed a sensitivity of 0.95 (95% CI [0.91, 0.97]) and a specificity of 0.76 (95% CI [0.65, 0.84]) in discriminating SCD from MCI participants. Conclusions: A signs and symptoms approach could be a useful tool for clinical neuropsychologists working in the field of MCI and dementia assessment.
... The SCD condition is associated with a 2-fold increased risk of future cognitive decline and dementia [2,3] and a higher prevalence of Alzheimer's disease (AD) biomarkers [4,5]. However, SCD is a broad category and has been studied with heterogeneous criteria and instruments, leading to variable findings as to its association with cognitive impairment and AD pathology [6][7][8]. Some features, known as SCD plus criteria, are associated with increased likelihood of AD, such as perceived decline in memory rather than in other cognitive domains, presence of worries associated with SCD, onset within the last 5 years [1,2,9]. ...
Background
subjective cognitive decline (SCD) refers to the subjective experience of cognitive decline in the absence of detectable cognitive impairment. SCD has been largely studied as a risk condition for cognitive decline. Empirical observations suggest that persons with SCD are heterogeneous, including individuals with early Alzheimer’s disease and others with psychological vulnerabilities and/or physical comorbidity. The semiology of SCD is still in its infancy, and the features predicting cognitive decline are poorly defined. The present study aims to identify subgroups of SCD using a data-driven approach and study their clinical evolution across 8 years.
Methods
the study population is the InveCe.Ab population-based cohort, including cognitively unimpaired people aged 70–74 years and followed for 8 years. Hierarchical cluster analysis (HCA) was carried out to identify distinct SCD subgroups based on nine clinical and cognitive features. Longitudinal changes by baseline SCD status were estimated using linear mixed models for cognitive decline and Cox proportional-hazard model for all-cause dementia risk.
Results
out of 956 individuals, 513 were female (54%); and the mean age was 72.1 (SD = 1.3), education was 7.2 (3.3), and 370 (39%) reported cognitive complaints (SCD). The HCA resulted in two clusters (SCD1 and SCD2). SCD2 were less educated and had more comorbidities, cardiovascular risk and depressive symptoms than SCD1 and controls. SCD2 presented steeper cognitive decline (Mini-Mental State Examination; β = −0.31) and increased all-cause dementia risk (hazard-ratio = 3.4).
Conclusions
at the population level, basic clinical information can differentiate individuals with SCD at higher risk of developing dementia, underlining the heterogeneous nature of this population even in a sample selected for a narrow age range, in a specific geographic area.
... Research has suggested that subjective cognitive decline (SCD), or the self-reported experience of subtle changes in cognitive functioning without any measurable changes in neuropsychological test performance [25], may be a preclinical marker of AD [3]. For example, individuals who endorse SCD have an increased risk of developing AD compared to the general population [3,49,53]. ...
... Research has suggested that subjective cognitive decline (SCD), or the self-reported experience of subtle changes in cognitive functioning without any measurable changes in neuropsychological test performance [25], may be a preclinical marker of AD [3]. For example, individuals who endorse SCD have an increased risk of developing AD compared to the general population [3,49,53]. Typically reported as increased confusion or memory loss, the prevalence of SCD among adults aged 60 and older is around 25% [50]. Therefore, SCD may prove to be an effective target for early intervention. ...
... Participant inclusion criteria for this specific study were as follows: (1) cognitively normal/healthy (NC/ SCD −) status at their baseline visit (e.g., no mild cognitive impairment, MCI), (2) no report of stroke, (3) had completed at least two cognitive assessments, (4) completed the questionnaire assessing memory complaints, and (5) at least 55 years of age at baseline. A clinical diagnosis of cognitive status was completed using a three-stage process including computer scoring of cognitive tests, clinical judgment by a neuropsychologist, and diagnostic classification by a clinician based on criteria of the joint working group of the National Institute on Aging and the Alzheimer's Association (NIA-AA) [39]. ...
Background: The identification of biomarkers and other mechanisms for early detection of Alzheimer's disease is critical to the development and further advancement of therapies and interventions targeted at managing symptoms and tracking the pathophysiology of disease. The endorsement of subjective cognitive decline (SCD) has emerged as a potential indicator of early change in cognitive status that may be predictive of future impairment at a time when measurable declines in neuropsychological performance cannot be detected. While there are numerous findings revealing sex differences in the prevalence of Alzheimer's disease, there is a paucity of research examining sex differences in SCD. Therefore, the goal of this project is to determine if the relationship between the endorsement of SCD and future cognitive changes differ as a function of biological sex.
Methods: A sample of 3019 male and female healthy older adults (2188 without SCD, 831 with SCD), with a mean follow-up time of 5.7 years, were included from the Rush Alzheimer's Disease Center Research Sharing Hub. Linear regressions were performed to determine group differences in baseline cognitive scores, while linear mixed effects models were computed to determine group differences in the rate of cognitive change over time.
Results: Individuals endorsing SCD had significantly lower baseline cognitive scores and increased rates of decline in all cognitive domains compared to those without SCD. Males exhibited significantly lower scores in baseline performance in global cognition, episodic memory, semantic memory, and perceptual speed regardless of SCD classification. Females with SCD were found to decline at significantly faster rates than both males with SCD and males and females without SCD in all cognitive domains over 15-year follow-up.
... This number is expected to double in the next 20 years, reaching 150 million by the middle of the century [2]. Importantly, the concept of AD has changed to recognize that AD is a continuum with a long preclinical phase of Subjective Cognitive Decline (SCD), a stage of mild cognitive impairment (MCI), and a dementia phase [3,4]. AD is characterized by memory and neuronal loss, difficulties in speaking, problem-solving, and other cognitive skills, along with changes in mood and behavior, which interfere with the person's daily performance. ...
Since 1906, when Dr. Alois Alzheimer first described in a patient “a peculiar severe disease process of the cerebral cortex”, people suffering from this pathology have been waiting for a breakthrough therapy. Alzheimer’s disease (AD) is an irreversible, progressive neurodegenerative brain disorder and the most common form of dementia in the elderly with a long presymptomatic phase. Worldwide, approximately 50 million people are living with dementia, with AD comprising 60–70% of cases. Pathologically, AD is characterized by the deposition of amyloid β-peptide (Aβ) in the neuropil (neuritic plaques) and blood vessels (amyloid angiopathy), and by the accumulation of hyperphosphorylated tau in neurons (neurofibrillary tangles) in the brain, with associated loss of synapses and neurons, together with glial activation, and neuroinflammation, resulting in cognitive deficits and eventually dementia. The current competitive landscape in AD consists of symptomatic treatments, of which there are currently six approved medications: three AChEIs (donepezil, rivastigmine, and galantamine), one NMDA-R antagonist (memantine), one combination therapy (memantine/donepezil), and GV-971 (sodium oligomannate, a mixture of oligosaccharides derived from algae) only approved in China. Improvements to the approved therapies, such as easier routes of administration and reduced dosing frequencies, along with the developments of new strategies and combined treatments are expected to occur within the next decade and will positively impact the way the disease is managed. Recently, Aducanumab, the first disease-modifying therapy (DMT) has been approved for AD, and several DMTs are in advanced stages of clinical development or regulatory review. Small molecules, mAbs, or multimodal strategies showing promise in animal studies have not confirmed that promise in the clinic (where small to moderate changes in clinical efficacy have been observed), and therefore, there is a significant unmet need for a better understanding of the AD pathogenesis and the exploration of alternative etiologies and therapeutic effective disease-modifying therapies strategies for AD. Therefore, a critical review of the disease-modifying therapy pipeline for Alzheimer’s disease is needed.
